Online advertising is the delivery of promotional marketing messages to consumers over the Internet. Examples of online advertising may include email marketing, search engine marketing, social media marketing, many types of display advertising, and mobile advertising. Personalized retargeting (also known as retargeting) is a form of online targeted advertising by which online advertising is targeted based on the previous actions of a consumer, which may include actions that led to a sale or conversion as well as those actions that did not. In many instances, online advertising campaigns utilize upselling techniques where advertisements are directed to more expensive items rather than items that are tailored for the consumer and their preferences.